I'm trying to use z88r on 2D quadrilateral meshes (from the command line, because it's going to be called from another program). I'm using a unix64 machine, and my installation of z88r runs quite happily on example b1 (either with -choly or -siccg), which is the closest to what I'm trying to do.

You have to specify the number of DOF per node in the z88i1.txt. Zero nodes is not allowed.
You also used DOF #0 in the z88i2.txt, which does not exist. And you have some double constraints applied at node 3 DOF #1 - displacement and force at the same time. Was this intended?
And you need to calculate the degrees of freedom from the number of nodes and dof per node, which should be 1886 in your case.

Please attach your project data ZIPPED, so we can have a detailed look at it.

Looks like a Memory Problem. Did you adjust the file z88.dyn? Please See the proper section in the manual.

No, because the section on z88.dyn said it would tell me if it ran out of memory. I have now tried increasing several of the parameters, but it made no difference. I have included z88.dyn in the attached .zip file.

The nodes which have zero DOF are the nodes which have constraints specifying that they can't move. I thought that this meant that they have zero DOF. Do they retain full (ie 2) DOF even when fixed?
Also, I tried altering my program to let fixed nodes retain 2 DOF, and it made no difference.

the z88i1.txt contains the information about nodes and elements, that's your structure file. The element no. 7 is defined to have 2 DOF per node, so you have to type in this number in the node list. It's totally independent from your boundary conditions / z88i2.txt.

In the z88i2.txt, where you write down your loads / constraints, you tell the solver which DOF is fixed. The DOF then still exists, but the displacement at the given node in the specified direction is set to zero. You must not "delete" DOF, but set them to zero.

If you put a load and a displacement constraint on the same node, this should not be a problem for the solver. I just asked if there was an error in numbering or if that was intended. However this is additional work for you, as the force will not have any effect on the structure.

The main problem is that your structure is invalid. The middle nodes are overlapping, that means there are two nodes where there should only be one (see screenshot).

This cannot work. Please keep that in mind and have a look at your mesh generator. You could use our superelement mesher to perform a mesh update and make your structure valid (this would mean you will have to apply all constraints again) or tweak your mesh generator to produce a valid mesh.

Kind regards,
SHautsch

P.S. Zipped files reduce our server load and disk usage, text/ascii files are just too inefficient - so we don't allow them to be uploaded

I've also kept track of which nodes are fixed, and not bothered exerting force on them.

The main problem is that your structure is invalid. The middle nodes are overlapping, that means there are two nodes where there should only be one (see screenshot).

That's embarassing
In my defence, the reason I didn't spot that is that z88o can't load fonts on my system (says "Cannot load Pango Font! STOP!" at startup, with the CLI giving the error "GdkGLExt-WARNING **: cannot load PangoFont") so it can't display any labels over the wireframe of the structure

Anyway, I've fixed the problem in my mesh generator, I think. The node count dropped by about 1/3, which suggests the duplicate nodes have been merged.
I've installed a CAD package which can view .dxf files, and used z88x to convert z88i1.txt to z88x.dxf. The results look good in the CAD program - no duplicate nodes.
However this hasn't made any difference at all to the results when running z88r

Your structure must not contain "free" nodes which are not connected to the rest of the structure.

Aha! That's done it! Once I get rid of those floating points, it works!
And for once it wasn't my code which was to blame - for some reason GMSH was deciding that it didn't like certain quads, and dropping them from the mesh, but still returning the points which they were made from.

I'm using Ubuntu 12.04 64-bit. If there's a known fix for Pango, then please do let me know, but otherwise don't worry about it, because I can still use z88o to view the stresses. And I'll mostly be feeding the z88o*.txt files into another program anyway - I'm just using z88o for diagnostics.

The font problem is known and results from changed X11 files, which were introduced with the newer versions of unix OS like Ubuntu. In fact this isn't a problem of Z88OS, but of the messed up X11 libs. We are waiting for a solution from the unix devs, but they don't seem to put a lot of work into that
For Z88Aurora, we use another way to display fonts and thus you could use Z88Aurora for displaying your results (or in fact for your whole calculations). You can run most of the executables of Z88Aurora from the command line and also convert the results to a Z88Aurora compatible format (have a look at z88ro2ag).

If you have questions on how to use Z88Aurora for your purposes, let us know.

For now, we consider your problem solved. Have fun with Z88 and get back to us if something is not working.